Advanced internal IDE IF for Atari ST(E)

   What  advanced features it offers:   better work with Compact Flash cards - what is currently most interesting IDE storage media.

       Very high data transfer speed:  reading over 3 Mbytes/sec - this allows high quality audio-video playback on STE.

  Background:  I designed first IDE IF for ST in 1992. It worked well with hard disks from that era. And can still work, even with very large capacity drives - many people think that IDE IF type is responsible for some disk size limits, while all it is on SW actually.
However, IDE is advanced a lot in meantime. We can talk now about ATA rather than IDE. And higher speeds result in that old timings (mostly based on bus timing of IBM AT - 6MHz CPU) are not good anymore. It is problem mostly with Compact Flash cards. Shortly: Atari ST(E) (and Falcon, actually any oldie) bus timings are not good for new ATA specs. Therefore it may happen that some CF cards will not work well with old type IDE adapters. Main problem is writing.
  Advanced IDE IF's timing is good for new CF cards, so expect that practically all quality ones will work fine.

AV playback:  it was my project in last couple months:   Movie playback
Certainly not something essential in life, but may show what our oldie is capable when pushed to limits.

Internal IF vs. external:  No need for extra power, adapter self costs usually less. Can combine with some expansions, with low additional cost - like TOS ROM upgrade, TOS switch. Can be faster.
External is simpler at start - just attach and use.

IDE (ATA) vs. ACSI hard disk IF:   Usually, Atari people says that ACSI is better, because IDE occupies CPU completely during transfers, what is in fact true, I mean: the second half of sentence. But in reality, no benefit of not occupied CPU during transfers with TOS - because all what it does is waiting to finish, when transfer via ACSI happens (DMA transfer).  Btw. even if ACSI transfers not use CPU for that, they slowdown CPU:  1MB/sec transfer slows down CPU about 25% .  IDE is usually faster, but ACSI can be very fast too - with ICD Link2 for instance.
However, IDE offers something not possible with ACSI (DMA):  syncronised direct transfers - because all is via CPU, we can have exact timing of transfers.
This is base of hi-color movie playback.  Another thing is superfast mode of Advanced IDE - using special, direct from IDE to RAM mode, what can be syncro too.


Features in detail:
Internal IDE (ATA) interface for hard disks, Compact Flash cards. Socket accessible from outside.
No disk capacity limit - it depends from used driver SW.
Advanced signal timing, good for Compact Flash cards. It needs special driver.
Possible to use popular hard disk drivers, like Hddriver, but only in regular AHDI mode - where no advanced timing.
With advanced mode over 3MB/sec reading speed is possible.
Autoboot with TOS 2.06, but possible to upgrade any TOS version for autoboot.
In case of some ST, it is best to upgrade TOS version to 1.04 - older ones aren't really good with hard disks.
TOS upgrade at minimal cost - because there is already ROM for advanced IDE modes.
And even space for 2 different TOS versions in machine, switchable.

The plan is to not sell interface kits in beginning. Instead it, I will build in it in machines self. Yes, it means shipping costs, but not many people can do building-in.

Because number of interested people affects overall costs, it would be good that interested people write me - so can do necessary component orders - prices are lower in bigger quantities, of course.

Estimated price of adapter self is 40-50 Euros (depends on batch quantity). Building in machine of basic IF with TOS upgrade, socket mounted in case about 20 Euros - if no extra demands.

Who may be interested: people with very old TOS versions (1.00-1.02), speed fanatics, STE owners wanting TOS 2.06 too, demo coders.

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   P. Putnik

Last revised: Jan 2013

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